(js) Fix computation of week number

NEWS

@@ -12,6 +12,7 @@ Bug fixes
  - [core] fixed condition in weekly recurrence calculator
  - [web] fixed mail settings persistence when sorting by arrival date
  - [web] disable submit button while saving an event or a task (#3880)
+ - [web] fixed computation of week number
 
 3.2.1 (2016-11-02)
 ------------------

UI/WebServerResources/js/Common/utils.js

@@ -325,6 +325,9 @@ Date.prototype.beginOfDay = function() {
     return beginOfDay;
 };
 
+/**
+ * See [SOGoUser firstWeekOfYearForDate:]
+ */
 Date.prototype.firstWeekOfYearForDate = function(localeProvider) {
   var firstWeekRule, dayOfWeek, januaryFirst, firstWeek;
 
@@ -354,19 +357,24 @@ Date.prototype.firstWeekOfYearForDate = function(localeProvider) {
   return firstWeek;
 };
 
+/**
+ * See [SOGoUser weekNumberForDate:]
+ */
 Date.prototype.getWeek = function(localeProvider) {
-  var firstWeek, previousWeek, weekNumber;
+  var firstWeek, previousWeek, weekNumber, clone;
 
-  firstWeek = this.firstWeekOfYearForDate(localeProvider);
-  if (firstWeek.getTime() < this.getTime()) {
-    weekNumber = 1 + Math.floor((this.getTime() - firstWeek.getTime()) / (86400000 * 7));
+  clone = new Date(this.getTime());
+  clone.addDays(6);
+  firstWeek = clone.firstWeekOfYearForDate(localeProvider);
+  if (firstWeek.getTime() < clone.getTime()) {
+    weekNumber = 1 + Math.floor((clone.getTime() - firstWeek.getTime()) / (86400000 * 7));
   }
   else
     {
       // Date is within the last week of the previous year;
       // Compute the previous week number to find the week number of the requested date.
       // The number will either be 52 or 53.
-      previousWeek = new Date(this.getTime());
+      previousWeek = new Date(clone.getTime());
       previousWeek.addDays(-7);
       firstWeek = previousWeek.firstWeekOfYearForDate(localeProvider);
       weekNumber = 2 + Math.floor((previousWeek.getTime() - firstWeek.getTime()) / (86400000 * 7));